how to get proper inputs

i have lately been running into lots of problems where i have a "string" and the items needs a "char" or vise versa, i have been trying to stay to "strings". I also think it has to do with the calls im using are old calls using the "char".
any help on how to open the file correctly with what i am using or if im using the wrong call to open the file a replacement

Code:

#include <iostream>
#include <fstream>
#include <string>

using namespace std;

int main()
{
	string fileName;
	cout << "Please enter file to open:";
	cin >> fileName;

	ifstream fin;
	string szLine = "";
	fin.open(fileName);			// this is where my problem stems from
	if (fin.fail())
	{	
		cout << " could not find filename\n";
		return -1;
	}
	while (getline(fin, szLine))
		cout << szLine;
	
	fin.close();
	

	system("pause");
	return 0;
}

You can always use fileName.c_str(). It will return a const char*, I believe.